The invention relates to a method for fabricating a germanium-on-insulator (GeOI) substrate and a germanium-on-insulator substrate.
Germanium-on-insulator structures are generally known in the art. EP 1 659 623 A1 discloses a method to fabricate a germanium-on-insulator (GeOI) substrate during which a germanium oxynitride (GeOxNy) layer is provided as a buried dielectric between a Ge layer and a handle substrate, e.g., a Si wafer. T. Signamarcheix et al in Applied Physics Letters 93, 022109 (2008) describes the advantageous effect of the presence of a GeOxNy layer underlying the active Ge layer concerning the electron mobility. Thus, this kind of substrate can advantageously be used for electronic devices based on n-MOS technology. It appears, however, that the hole mobility became affected by the presence of the GeOxNy layer so that concerning p-MOS devices, this kind of substrate is less suited.
Accordingly, there is a need for improved germanium-on-insulator substrates and these are now provided by the present invention.